It is unavoidable that humans emanate odor. This odor is produced by a chemical mixture, excreted through the skin and sweat glands, which contains ammonia and amino acids. It is well known that wild game animals have a keenly developed sense of smell and can readily distinguish odors that are not indigenous to their natural habitat. Hunters seeking to get into close proximity to game animals have sometimes tried special clothing in an attempt to either mask or absorb their natural body odor. In the related prior art, Sesselmann, U.S. Pat. No. 5,539,930, discloses a system of special clothing for hunters designed to absorb body odor. Fore, U.S. Pat. No. 5,891,391, discloses a clothing deodorizer for deer hunters.
Devices designed for personal protection against environmental hazards caused by ammonia fumes are also well known in the prior art. However, none of these devices is suitable for detecting gaseous ammonia when it is present in only parts per billion, which is the order of magnitude of those concentrations of ammonia found in human body odor. The American Gas Co., for example, markets ammonia detectors used for personal protection. When exposed to gaseous ammonia in the sensitivity range of 25 ppm for five minutes, the indicator chemicals in them change color from yellow to blue. However, when American Gas & Chemical Co. detectors were tested to see if they could be used to detect ammonia and amino acids at the concentrations at which they are found in human body odors, no change of color occurred. Further, after these detectors had been exposed to high concentrations of ammonia which changed the color of their indicator chemicals to blue and after they were then removed from these high concentrations, their color changed back to yellow.
Like the indicator chemicals in the American Gas & Chemical Co. detectors, those used in the paint or coating compositions disclosed by Mallow et al., U.S. Pat. Nos. 5,183,763 and 5,322,797 (hereinafter “Mallow”), when incorporated into such a detector, have proven themselves to be useful only for indicating the presence of ammonia and/or amino acid vapors in relatively high concentrations.
Indeed, this situation exists, notwithstanding Mallow's teaching that his chemical composition, when applied to selected surfaces as a paint, can serve as a passive detector for extremely low concentrations of vapor or liquid reactants, such as ammonia.
Specifically, tests were done by the applicant on detectors in which one of Mallow's compositions served as the indicator chemical, with this composition being sealed within the detector in such a way that it could not be activated by airborne chemicals from the atmosphere/outside environment. Rather, because of the manner in which the detector was attached to the test subject's body, the composition could only be activated by compounds released through the wearer's skin, thereby limiting the exposure of Mallow's composition to the constituents of human body odor. These tests showed no color changes in Mallow's compositions when they were exposed, for intervals of up to four hours at a time, to ammonia and amino acids at the concentrations at which they are found in human body odor.
Moreover, each of Mallow's compositions, once it has changed color as a result of exposure to sufficiently high concentrations of ammonia or other nitrogen-type compounds, is known to revert back to its original color (e.g., yellow) after a period of time. Consequently, valuable information may be lost before a user realizes that a spike in the release of ammonia or the like has occurred.